There is a need for mechanisms for positioning the load carrying floor of a vehicle, such as a trailer, relative to a dock, for facilitating movement of cargo from the vehicle floor to the dock floor or from the dock floor to the vehicle floor. A principal object of the present invention is to provide an improved mechanism or system for moving a vehicle floor into alignment with a dock floor. It is known to equip trailers with reciprocating slat conveyors and using the conveyors together for loading and unloading the trailer. The use of a slat conveyor on the dock together with a slat conveyor within a trailer or other vehicle is the subject matter of Copending application Ser. No. 09/076,505, filed concurrently, herewith on May 12, 1998, and entitled Vehicle/Dock Loading/Unloading Conveyor System now U.S. Pat. No. 5,911,555, granted Jun. 15, 1999. The alignment mechanism or system of the present invention has a particular utility for aligning a vehicle/conveyor with a dock/conveyor.
There are basically two kinds of reciprocating slat conveyors on the market today. The first and most popular reciprocating slat conveyor is characterized by a plurality of elongated conveyor slats which are divided into sets and groups. By way of typical and therefore nonlimitive example, a conveyor of this type may include eight groups and three sets, with each group comprising one slat from each set. That is, each group includes a set "1" slat, followed by a set "2" slat followed by a set "3" slat. The groups extend side-by-side across the conveyor. The conveyor slats are supported on a conveyor frame, each for longitudinal back and forth movement. A drive mechanism is provided for the conveyor slats. The drive mechanism operates to move all of the conveyor slats in unison, in a first direction, for conveying a load that is on the conveyor. Then, the conveyor slats are retracted, one set at a time, back to a start position. As each set is retracted, the remaining sets are stationary and function to hold the load in position. Following retraction of all sets, the conveyor slats are again moved in unison in the first direction for conveying the load on the conveyor an additional step. Examples of this type of conveyor are disclosed by U.S. Pat. No. 4,821,868, granted Apr. 18, 1989, to Raymond Keith Foster, and entitled Drive/Frame Assembly For A Reciprocating Floor; by U.S. Pat. No. 5,165,524, granted Nov. 24, 1992, to Raymond Keith Foster, and entitled Reciprocating Floor Conveyor; and by U.S. Pat. No. 5,605,221, granted Feb. 25, 1997, to Raymond Keith Foster and entitled Drive Unit With Bearing Mount. As is disclosed by these patents, sometimes a transverse drive beam is provided for each set of conveyor slats. Each transverse drive beam is connected to its set of conveyor slats and to a linear hydraulic drive unit for reciprocating the drive beam and the conveyor slats back and forth longitudinally of the conveyor. U.S. Pat. No. 5,165,524 discloses connecting the linear hydraulic drive units to one conveyor slat from each set at a location spaced from the transverse drive beams. The force generated by each drive unit is transmitted to the conveyor slat to which the drive unit is connected and from that conveyor slat to the transverse drive beam to which the conveyor slat is connected and onto the remaining slats of the set. U.S. Pat. No. 5,605,221 discloses providing a separate linear hydraulic drive unit for each conveyor slat.
The second type of reciprocating slat conveyor provides a continuous movement of the load on the conveyor. A majority of the conveyor slats are always moving in the conveying direction while a minority of the conveyor slats are retracting. An example of this type of conveyor is disclosed by pending U.S. application Ser. 08/827,620, filed Apr. 9, 1997, by Raymond Keith Foster, et al., and entitled Continuously Advancing Reciprocating Slat Conveyor.
U.S. Pat. Nos. 4,821,868; 5,165,524, 5,605,221, 5,911,555, and application Ser. No. 08/827,620 are hereby incorporated herein by this reference to them.